FACULDADE DE MEDICINA DA UNIVERSIDADE DE COIMBRA

MESTRADO INTEGRADO EM MEDICINA – TRABALHO FINAL

MARTA GARCIA COSTA

JUVENILE OSSIFYING FIBROMA COMPROMISING THE ZINN´S

ANNULUS

CASO CLÍNICO

ÁREA CIENTÍFICA DE OTORRINOLARINGOLOGIA

Trabalho realizado sob a orientação de:

JOÃO CARLOS RIBEIRO

MAFALDA DA SILVA FERREIRA

ABRIL/2018

JUVENILE OSSIFYING FIBROMA COMPROMISING THE ZINN´S ANNULUS

Marta Garcia Costa1, Mafalda da Silva Ferreira2, João Carlos Ribeiro1,2

1Faculty of Medicine, University of Coimbra, Portugal

2Department of Otorhinolaryngology, Centro Hospitalar e Universitário de Coimbra,

Portugal

Contact: marta.gcosta@hotmail.com

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Abstract

Juvenile ossifying fibroma is a rare fibro-osseous neoplasm that mainly affects the

bones of the orbit and paranasal sinuses. Although benign, it presents a locally aggressive

behavior and a high relapse rate. In specific locations, it poses a great treatment challenge so

that early diagnosis and multidisciplinary treatment are crucial to improve the prognosis and

delay clinical sequelae.

Sinuses and medial orbit neoplasms diagnosis is made from clinical, imaging and

histopathological exams. CT-scans and preoperative biopsy play an important role. The

treatment of choice is a surgical resection. Endoscopic nasal approach is recommended because

of its lower morbidity. However, there are some cases in which other options must be

considered to perform resection as complete as possible and preserve function.

We report a case of a young woman with psammomatoid type juvenile ossifying

fibroma of the medial aspect of the Zinn´s annulus, undergoing surgical optic nerve

decompression, combining a transcranial bicoronal open and endonasal endoscopic surgery.

Functional success in clinical practice dealing with juvenile ossifying fibroma of the

orbit is associated to a rigorous preoperative planning, multidisciplinary approach, and the use

of the most appropriate techniques for each case, depending mostly on the characteristics of the

tumor, especially size and location.

Keywords: Paranasal Sinus Neoplasms; Fibroma, Ossifying; Natural Orifice Endoscopic

Surgery; Rhinosurgery

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Introduction

Juvenile Ossifying Fibroma (JOF), a variant of Ossifying Fibroma (OF), is a rare

benign fibro-osseous neoplasm that is divided into two subgroups, the trabecular and the

psammomatoid, distinguished by clinical and histological characteristics. Pathogenesis

mechanisms are still not completely understood.1,2 It can present a fast growth with high

vascularization,2 with destruction of the adjacent structures, resulting in important loco-regional

destruction. It is characterized by an early age appearance, usually ranging between 5 and 15

years, and a slightly male preference.3 It mainly affects the orbital bones and paranasal

sinuses.3,4

The optic canal, with 10mm length, contains the optic nerve, ophthalmic artery and

sympathetic plexus.5 The optic nerve is ensheathed in all three meningeal layers in its

extracranial portion, as an extension of the brain, when damaged may result in irreversible

blindness. It can be anatomical divided in possible sites of injury, intracanalicular is the most

vulnerable to external compression.5,6

JOF signs and symptoms depend on its location and size, ranging from nasal

obstruction, rhinorrhea, epiphora, to exophthalmia, diplopia and facial dysmorphisms.2,3

Differential diagnosis of JOF is made with traumatic optic neuropathy, inflammatory

conditions, idiopathic intracranial hypertension,5,6 osteomas and fibrous intraosseous lesions

such as fibrous dysplasia, desmoplastic fibroma, central giant cell granuloma and cherubism.7

A correct differentiation is critical because the treatments protocols are entirely different in

some cases.8

Imaging plays an important role, not only in JOF diagnosis, but also for a more reliable

preoperative evaluation, determination of possible anatomical variations,9 preparing the

neuronavigation surgical aid and follow-up. CT-scan is the gold-standard to detect and stipulate

the tumor’s size. MRI imaging is recommended for ruling out cerebral or orbital invasion .2

4

JOF presents a high rate of recurrence, so it is essential to obtain an early diagnosis and

treatment.7,10 In CT imaging, it presents as a lesion predominantly of soft tissues, well

circumscribed with calcifications. In MRI, it exhibits low/medium intensity signal with

enhancement after injection of contrast (gadolinium). Histologically, it is characterized by the

presence of proliferative fibrous cell tissue and irregular osteoid strands containing osteoblasts

with a broad variation of mineralization. The psammomatoid variant presents rounded

calcifications called psammomatoid bodies.11

Definitive diagnosis is made by the correlation between clinical, imagiological and

histopathological findings.3,8,11 Whenever possible, a preoperative biopsy should also be

performed.10

Treatment of choice is surgical, aiming the total removal of the tumor to avoid future

relapses. Endoscopic endonasal surgery represents the first line since it allows good exposure

in a minimally invasive manner, reducing morbi-mortality rates.12 Despite the evolution in

surgical techniques, it still presents a high rate of recurrence. Although there are no reported

cases of malignant transformation or metastasis13, radiation therapy is not indicated and may

increase the risk of malignancy and potential harmful late effects.2,13,14

We report a case of a 26-year-old girl with a psammomatoid type recurrent JOF who

underwent optic nerve decompression via a combined endoscopic endonasal and transcranial

open approach with good clinical outcome.

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Case report

A previously healthy 26-year-old Caucasian female presented to the emergency

department exhibiting first time intense headaches in 2013. She was studied and a cranial MRI

was performed revealing a 65 mm spheno-ethmoidal neoplasm.

After joint clinical decision, she underwent surgical treatment by a combined endonasal

endoscopic and open transcranial approach, with subcomplete resection of the Zinn annulus

lesion, resulting in a complete symptomatic resolution. Through a binostril approach, it was

performed a complete spheno-ethmoidectomy. The uncinate process was removed, and a

middle meatal antrostomy provided access to the inferior and medial orbital walls. After the

removal of the lamina papyracea, the optic canal was exposed in a antero-posterior direction,

up to the lateral edge of the tuberculum sellae, by a dissector and gentle but extensive drilling

with diamond burrs.

Optic carotid recess and latero-superior aspect of optic canal were not reachable.

Histopathological findings indicated psammomatoid JOF (figure 1).

Figure 1: Optic microscopic view of patient’s biopsy sample showing proliferative fibrous cell tissue containing

rounded calcifications resembling psammomatoid bodies.

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The patient returned one year later complaining of diplopia, presenting papilledema and

right proptosis that resolved with systemic corticotherapy.

In 2016, she reported a progressive decrease in the right visual acuity, diplopia, and

exhibited an afferent pupillary defect and chromatic alteration of reds. MRI imaging confirmed

a neoformation centered on the ethmoid-frontal region growing into the naso-ethmoidal surgical

cavity, with 6.2 cm in diameter, extending to the base of the skull and involving the right orbit

(figure 2). The same combined approaches via open bifrontal craniotomy and endoscopic

endonasal surgery were used, with optic nerve subtotal decompression. Transcranial

complementary route was performed to achieve the decompression of the supero-lateral

segment of the optic canal. Sphenoidectomy was widened after a large posterior septectomy

with exposure of the optic canal up to the lateral edge of the tuberculum sellae (figure 3). The

medial aspect of the optic nerve was uncovered till the annulus of Zinn.

Figure 2: Pre-operative contrasted MRI of the perinasal sinuses presenting a tumor lesion affecting frontal

and ethmoidal sinuses with extension to the skull base without involving the dura mater. Equally observed

extension of the tumor into the apical side of the optic nerve (red arrows).

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She was discharged on the 7th day of hospitalization, with no focal neurological

symptoms. Visual acuity was maintained and no papilledema, signs of CSF fistula, headache

or epistaxis were present.

Patient maintains a regular follow-up with otorhinolaryngology, ophthalmology and

neurosurgery. After 24 months, she is currently asymptomatic.

Informed consent was obtained from the patient.

Figure 3: Postoperative CT of the orbits showing evidence of bilateral maxillary and ethmoidal sinusectomy

(red arrows).

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Discussion

Juvenile ossifying fibroma involving the orbit nerve is a rare, potentially facial

disfiguring, visual impairment and fatal tumor that requires a multidisciplinary individual

treatment decision according to each patient and tumor location.

JOF may exhibit the trabecular or the psammomatoid histological pattern, the case

reported here is compatible with the psammomatoid type. Definite diagnosis can be challenging

but is crucial to guide the treatment.

The only current and first-line curative treatment is complete surgical excision of the

lesion preferably by endonasal endoscopy. This approach provides an excellent visualization of

the operative field, preservation of the olfactory function, avoidance of cosmetic morbidity and

also avoidance of brain retraction, allowing lesion’s total resection most of the times.15

Endonasal endoscopic surgery, although representing a low morbidity option and

adequate exposure of the medial aspects of orbital apex, still presents complications, such as

nasal sinus hemorrhage, rhinorrhea, subcutaneous emphysema and visual deterioration.6

Guided imaging systems revolutionized endoscopic surgery by minimizing operative time and

the possibility of hemorrhage through better visualization of tumor margins.4

However, in cases such as the one described, due to the location and expansion of the

tumor, a combined approach should be considered.10 Particularly in cases affecting the anterior

wall of the frontal sinus or supraorbital recess, encasing the optic nerve or invading the skull

base, an external approach is often needed. Contribution of other specialties, such as

ophthalmology and neurosurgery, may be necessary in order to facilitate resection, decrease the

likelihood of sequelae and reduce patient’s recovery time. Optic nerve decompression is usually

indicated if continuity of the nerve is not disrupted and there’s evidence of worsening of visual

acuity. It must be considered early in the disease to prevent nerve atrophy and its

consequences.5,12

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Optic nerve decompression surgery can present some challenges such as the close

relationship of the optic nerve and the paracavernous internal carotid artery that may limit the

access.6 Another difficulty is the possible variation of the ophthalmic artery’s position within

the canal that requires caution when incising the optic nerve sheath.5 Also, the degree of

sphenoid sinus pneumatization influences the amount of bone removal from the optic canal and

even when it’s feasible to access and decompress from its medial aspect, extensive drilling is

required. A high-speed drill shaft can cause alar burns if prolonged manipulation so it is critical

to use abundant irrigation to avoid thermal damage to the nerve.5,6

The chosen approach will depend essentially on the location and size of the tumor. It

should be emphasized the need of advanced technical expertise and experience and awareness

of unpredictable intra-operative findings that may demand conversion of endoscopic into an

open procedure.15

Prognosis is still uncertain, it is known that more aggressive lesions are less common

in adults but there is still a high rate of relapse, so a wide excision and, if necessary, additional

reconstructive surgery is recommended in order to preserve the functionality and aesthetics.4

Rigorous long-term follow-up should be performed even in the absence of any neurologic

deficit.

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Conclusion

Juvenile Ossifying Fibroma (JOF) is a rare benign fibro-osseous neoplasm, classified

as a variant of ossifying fibroma, that occurs at earlier ages. It presents locally aggressive

behavior and high rate of relapse. Radical resection surgery is widely considered the treatment

of choice.

Endonasal endoscopic surgery currently represents the safest and most effective

treatment, being minimally invasive and intended to restore function in inferior and medial JOF

optic nerve tumors. In cases of optic nerve non-traumatic compression, it must be performed

earlier in order to prevent nerve atrophy. The use of imaging exams (CT) for preoperative

planning and use of navigation systems allows surgical technique optimization and risk

minimization.

We conclude that a successful management of difficult cases of JOF requires a

multidisciplinary teamwork, strict preoperative planning and the use of the most adequate and

advanced surgical techniques. This way it is possible to avoid future relapses, ensure function

and thus provide significant improvement in the patient’s quality of life.

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Acknowledgments

A particular acknowledgment to Professor Doutor João Carlos Ribeiro and Dr.ª

Mafalda Ferreira for their guidance and readiness through this process. Their advice and support

made this work possible. A word of appreciation to Drª Maria José Abreu Julião for providing

the data concerning the patient’s histological sample.

A special word of acknowledgment to my family and friends that always believe in

me and encourage me to do better, no matter the obstacles. I warmly thank them for being

present in each and every one of the steps that made this long journey so rewarding. To my

parents, with all my heart, huge thanks for their love and wisdom through the years.

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